dennypayne wrote:dynamo12 wrote:A 400Mhz guard band is absolutely ridiculous. If you cannot operate radio equipment with 400Mhz guard you have no business operating anything RF - period.
Let's be clear. Radio Alt STARTS at 4200 (and as another 200 to work with). These new bands are coming in somewhere around 3800.
400Mhz would get you laughed out of the room anywhere else. The idea that a radio altimeter needs 200MHz + 400Mhz (or more) on each side is absolutely ridiculous especially in this band area - that's nearly 1,000Mhz of bandwidth.
Normal guard bands might be something like 0.1Mhz to 20Mhz in other domains.
And yet according to the graph posted by kalvado, that’s the reality of what is happening. Fixating on what “should” be the case is useless at this point.
But as long as we’re talking “shoulds” - safety should be paramount over making money, and ideally the FCC and FAA should have collaborated earlier on this issue. But here we are…
Grandfathering can go only that far. Issue was raised a while ago, there is a formal letter from 2017 on the subject. My impression is FAA is plainly not qualified in the subject for meaningful collaboration.